The extinction of the Trazegnies dynasty led to the sale of the castle to a coal mine which partitioned off its land, leaving the castle itself to the Belgian state. It had become derelict by 1926 and suffered severe damage from subsidence as a result of underground mining. However, a civic association called the "Friends of Trazegnies Castle" (Les Amis du Château de Trazegnies) successfully opposed its destruction and began a gradual programme of restoration with the support of the Walloon Region. The castle is currently open to the public on designated days.